Variable valve system

ABSTRACT

The present disclosure relates to a variable valve system applying a continuously variable valve timing apparatus and a two-step type variable valve lift apparatus. The variable valve system may be applied to an engine that a rotational motion of a cam being formed or disposed at a camshaft so as to rotate together with the camshaft is converted to a reciprocating motion of a valve for opening/closing a combustion chamber. The variable valve system may include the two-step type variable valve lift apparatus making a lever motion, and a continuously variable valve timing apparatus changing phase of the camshaft connected with a rotor as the rotor rotates by rotating a vane formed at the rotor. In particular, one end of the valve lift apparatus is rolling-contacted with the cam and the other end is contacted with the valve so as to realize one of two lifts of the valve.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of Korean Patent Application No. 10-2015-0177475, filed on Dec. 11, 2015, which is incorporated by reference in its entirety.

FIELD

The present disclosure relates to a variable valve system. More particularly, the present disclosure relates to a variable valve system for varying lift or timing of a valve.

BACKGROUND

The statements in this section merely provide background information related to the present disclosure and do not constitute prior art.

Generally, a continuously variable valve timing (CVVT) apparatus refers to an apparatus which adjusts opening and closing timing of a valve of an engine. Particularly, as the CVVT apparatus controls an intake valve or an exhaust valve in accordance with a driving condition, output of the engine and fuel efficiency may be improved, and exhaust gas may be reduced.

Meanwhile, appropriate operations of the intake valve or the exhaust valve are determined according to rotation speed of the engine. That is, lift and open/close timing of the valves are properly controlled according to rotation speed of the engine. A variable valve lift (VVL) apparatus has been developed in which the valves are operated for various lifts according to rotation speed of the engine for improved operations of the valves according to rotation speed of the engine.

On the other hand, in case that a plurality of cams having each different profile are disposed on a camshaft, composition to select a cam for operating an intake valve or an exhaust valve may be to be complex and interference between constituent elements may be occurred. Further, in case that a variable valve lift apparatus which makes a lever motion by rolling-contacting a cam having uniform profile realizes lever motions to be same to or more than three such that the valve lift is varied to be same to or more than three steps, composition of a hydraulic circuit to supply hydraulic pressure for realizing operation of the variable valve lift apparatus may be to be complex. In addition, it may be limited to improve fuel consumption as a continuously variable valve timing apparatus only performs a control for retarding a closing timing of an intake valve.

SUMMARY

The present disclosure provides a variable valve system having advantages of applying a continuously variable valve timing apparatus and a variable valve lift apparatus being configured by a two-step type.

A variable valve system according to one form of the present disclosure may be applied to an engine being configured that a rotational motion of a cam being formed or disposed at a camshaft so as to rotate together with the camshaft is converted to a reciprocating motion of a valve for opening/closing a combustion chamber. The variable valve system may include a two-step type variable valve lift apparatus making a lever motion and being configured that one end thereof is rolling-contacted with the cam and the other end thereof is contacted with the valve so as to realize lift of the valve to one of two lifts of the valve; and a continuously variable valve timing apparatus changing a phase of the camshaft connected with a rotor as the rotor rotates by rotating a vane formed at the rotor so as to selectively change opening/closing timing of the valve.

The variable valve system may be applied to an intake side of the engine and the valve may be an intake valve which is operated so as to supply intake air into the combustion chamber.

The variable valve system may be applied to an exhaust side of the engine and the valve may be an exhaust valve which is operated so as to discharge exhaust gas from the combustion chamber.

The continuously variable valve timing (CVVT) apparatus may be an electric continuously variable valve timing apparatus which is operated electrically.

The continuously variable valve timing apparatus may be an intermediate phase CVVT which is operated by hydraulic pressure so as to have a parking position which is not a maximal advance or a maximal retard but an intermediate phase between them.

The two valve lifts being realized by the two steps type variable valve lift apparatus may be the high lift and the low lift, and the two steps type variable valve lift apparatus may be operated to realize the high lift by supplying hydraulic pressure and to realize the low lift by releasing the hydraulic pressure.

The two valve lift being realized by the two steps type variable valve lift apparatus may be the high lift and the low lift, and the two steps type variable valve lift apparatus may be operated to realize the low lift by supplying hydraulic pressure and to realize the high lift by releasing the hydraulic pressure.

The two steps type variable valve lift apparatus may include an outer body selectively making a lever motion depending on the rotation of the cam and being configured that the valve is connected with one end thereof, a rotation axis of the lever motion is disposed at the other end thereof, and an inside space is formed thereat; an inner body disposed in the inside space of the outer body and adapted that one end thereof is rotatably connected with the one end of the outer body; a connecting shaft disposed to penetrate the one end of the outer body and the one end of the inner body so as to connect the outer body with the inner body; and a lost motion spring provided to return the inner body being relatively rotated with the outer body around the connecting shaft.

The inner body may make a lever motion together with the outer body depending on the rotation of the cam around the rotation axis of the lever motion of the outer body during being selectively fixed to the outer body, and the inner body may make a lever motion alone depending on the rotation of the cam around the connecting shaft during releasing from the outer body.

The two steps type variable valve lift apparatus may realize the high lift of the valve as the outer body makes a lever motion together with the inner body and may realize the low lift of the valve as only the inner body makes a lever motion around the connecting shaft.

The inner body may form an inside space and the two steps type variable valve lift apparatus further include a roller disposed in the inside space of the inner body and rotatably connected with the inner body so as to rolling-contact with the cam so that the inner body makes a lever motion depending on the rotation of the cam.

Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.

DRAWINGS

In order that the disclosure may be well understood, there will now be described various forms thereof, given by way of example, reference being made to the accompanying drawings, in which:

FIG. 1 is a schematic diagram of a variable valve system according to an exemplary form of the present disclosure;

FIGS. 2A-2C are partial schematic diagrams of a continuously variable valve timing apparatus according to an exemplary form of the present disclosure;

FIG. 3 is a drawing showing operation regions of a continuously variable valve timing apparatus according to an exemplary form of the present disclosure;

FIG. 4 and FIG. 5 are hydraulic circuit diagrams of a continuously variable valve timing apparatus according to an exemplary form of the present disclosure;

FIG. 6 is a top plan view of a two steps type variable valve lift apparatus according to an exemplary form of the present disclosure;

FIG. 7 is a cross sectional side view of a two steps type variable valve lift apparatus according to an exemplary form of the present disclosure; and

FIG. 8 is a hydraulic circuit diagram of a two steps type variable valve lift apparatus according to an exemplary form of the present disclosure.

The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.

DETAILED DESCRIPTION

The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features.

FIG. 1 is a schematic diagram of a variable valve system according to one form of the present disclosure.

As shown in FIG. 1, a variable valve system 1 includes a continuously variable valve timing apparatus (CVVT apparatus, 100) and a variable valve lift apparatus (VVL apparatus, 200) being configured by a two-step type.

The variable valve system 1 is applied to an engine being configured that a rotational motion of a camshaft 3, which is connected with a crankshaft (not shown) by a chain or a belt and is rotated by rotation of the crankshaft, is converted to a reciprocating motion of a valve 50 for opening/closing a combustion chamber (not shown). In addition, the valve 50 makes a reciprocating motion depending on rotation of a cam 30 which is formed or disposed at the camshaft 3 so as to rotate together with the camshaft 3. Further, the two-step type variable valve lift apparatus 200 makes a lever motion depending on rotation of the cam 30 such that the valve 50 makes a reciprocating motion.

The cam 30 includes a high cam 32 having a profile for realizing high lift of the valve 50 and a low cam 34 having a profile for realizing low lift of the valve 50. Generally, the valve 50 is opened/closed by the high cam 32 when the time (valve duration) opening the valve 50 is desired to be long, and the valve 50 is opened/closed by the low cam 34 when the time (valve duration) opening the valve 50 is desired to be short.

The valve 50 is an intake valve being operated so as to supply intake air to the combustion chamber of the engine or an exhaust valve being operated so as to discharge exhaust gas form the combustion chamber. In FIG. 1, a general configuration of constituent elements which construct an exhaust portion of the engine, but the configuration of the constituent elements is not limited thereto and the variable valve system 1 is able to apply to the intake portion or the exhaust portion of the engine. In addition, it may be determined that the variable valve system 1 is selectively applied to one or both of the intake portion and the exhaust portion by a design of a person of an ordinary skill in the art.

The continuously variable valve timing apparatus 100 is a device which is operated to selectively change opening/closing timing of the valve 50, and the two-step type variable valve lift apparatus 200 is a device which is operated to vary lift of the valve 50 to high lift or low lift.

FIGS. 2A-2C are partial schematic diagrams of a continuously variable valve timing apparatus according to one form of the present disclosure.

As shown in FIGS. 2A-2C, the continuously variable valve timing apparatus (100, CVVT apparatus) basically includes a rotor 120, a stator 110, and a vane 122. In addition, a gear or a chain sprocket may be mounted to the CVVT apparatus 100.

The gear or the chain sprocket may be connected with a gear or a sprocket, which rotates together with crankshaft, by a belt or a chain so as to synchronize rotation of the engine with rotation of the camshaft. In addition, a relative phase between the rotor 120 and the stator 110 changes as the vane 122 formed at the rotor 120 is moved by hydraulic pressure such that the rotor 120 rotates, and opening/closing timing of the valve 50 is controlled with variable as phase of the camshaft 3 connected with the rotor 120 is changed in a circumference direction.

The basic configuration and operation of the CVVT apparatus 100 is well known to a person of an ordinary skill in the art, so detailed description thereof will be omitted.

Meanwhile, an electric CVVT apparatus which is electrically operated or an intermediate phase CVVT apparatus 100 which is a CVVT apparatus being configured by hydraulic pressure type improving reactivity may be applied to the variable valve system 1 according to another form of the present disclosure. Herein, the electric CVVT apparatus is well known to a person of an ordinary skill in the art, so detailed description thereof will be omitted.

Hereinafter, the intermediate phase CVVT apparatus 100 will be described referring FIG. 3 to FIG. 5.

FIG. 3 is a drawing showing operation regions of a continuously variable valve timing apparatus according to one form of the present disclosure.

As shown in FIG. 3, the CVVT apparatus 100 further includes a first chamber 130 and a second chamber 132.

The first chamber 130 and the second chamber 132 are spaces which are surrounded by the stator 110, the rotor 120 and the vane 122 such that hydraulic pressure is supplied thereto, and the vane 122 is operated depending on difference between hydraulic pressure being supplied to the first chamber 130 and hydraulic pressure being supplied to the second chamber 132. In addition, the rotor 120 rotates toward an advance direction changing phase of the cam 30 such that the valve timing of the valve 50 is advanced when hydraulic pressure is supplied to the first chamber 130, and the rotor 120 rotates toward a retard direction changing phase of the cam 30 such that the valve timing of the valve 50 is retarded when hydraulic pressure is supplied to the second chamber 132. In FIG. 3, the advance direction (A), the retard direction (R), and the rotating direction (C) of the camshaft 3 are illustrated with arrows.

The CVVT apparatus 100 is the intermediate phase CVVT apparatus 100 having a parking position which is not a maximal advance or a maximal retard but an intermediate phase between them, and the rotor 120 of the intermediate phase CVVT apparatus 100 may have a rotation angle of about 50 degree as operation regions for relatively moving the stator 110 toward the advance direction (A) and a rotation angle of about 30 degree as operation regions for relatively moving the stator 110 toward the retard direction (R). This is to increase operation regions in comparison with an ordinary CVVT apparatus having a parking position which is the maximal advance or the maximal retard. Further, if the parking position is to be the intermediate phase, reactivity of changing the phase of the cam 30 by rotation of the rotor 120 such that the valve timing is advanced or retarded is relatively improved in comparison with the parking position which is the maximal advance or the maximal retard.

FIG. 2A shows a state that the rotor 120 is operated to realize the valve opening/closing timing with the maximal advance, and FIG. 2B shows a state that the rotor 120 is parked on the intermediate phase, and FIG. 2C shows a state that the rotor 120 is operated to realize the valve opening/closing timing with the maximal retard.

The operation states are realized depending on strength of hydraulic pressure being respectively supplied into the first chamber 130 and the second chamber 132.

FIG. 4 and FIG. 5 are hydraulic circuit diagrams of a continuously variable valve timing apparatus according to the present disclosure.

As shown in FIG. 4 and FIG. 5, the intermediate phase continuously variable valve timing apparatus 100 further includes a lock pin 140, a controller 5, a hydraulic pump 7, a rotor control valve 320, a lock pin control valve 330, a main oil passage 400, a lock pin control oil passage 410, a first rotor control oil passage 420, a second rotor control oil passage 430, a first regulating valve 441, and a second regulating valve 442.

The lock pin 140 is operated to selectively park the rotor 120 depending on supplied hydraulic pressure. At this time, a parking position of the rotor 120 by the lock pin 140 is the intermediate phase. In addition, the operation of the lock pin 140 by the hydraulic pressure is for a fail-safe control of the intermediate phase CVVT apparatus 100 and is separately performed with an electrical operation of the lock pin 140 by a solenoid (not shown).

The controller 5 may be an electronic control unit (ECU) generally controlling electronic devices of a vehicle.

The hydraulic pump 7 pumps oil according to a control of the controller 5 so as to supply hydraulic pressure being desired to an operation of the intermediate phase CVVT apparatus 100. In addition, the hydraulic pump 7 may be a general hydraulic pump which rotates by receiving torque of the crankshaft.

The rotor control valve 320 is disposed to receive hydraulic pressure from the hydraulic pump 7. In addition, the rotor control valve 320 selectively supplies hydraulic pressure such that the rotor 120 relatively rotates with respect to the stator 110. That is, the rotor control valve 320 is opened or closed according to a control of the controller 5 such that hydraulic pressure is selectively supplied from the hydraulic pump 7 into the first chamber 130 and the second chamber 132.

The lock pin control valve 330 is disposed to receive hydraulic pressure from the hydraulic pump 7. In addition, the lock pin control valve 330 selectively supplies hydraulic pressure such that the lock pin 140 performs or releases the parking of the rotor 120. That is, the lock pin control valve 330 is opened or closed according to a control of the controller 5 such that hydraulic pressure is selectively supplied from the hydraulic pump 7 into the lock pin 140. Further, the lock pin 140 releases the parking of the rotor 120 during receiving hydraulic pressure to be equal to or more than a set value from the lock pin control valve 330 and performs the parking of the rotor 120 during receiving hydraulic pressure to be less than the set value. Furthermore, in case that the lock pin 140 receives hydraulic pressure to be less than the set value, the parking of the rotor 120 may be performed by an elastic member 145 which pushes the lock pin 140 toward a direction to face to hydraulic pressure.

The main oil passage 400 is adapted that one end thereof is communicated with the hydraulic pump 7 and the other end thereof is branched by two so as to be respectively communicated with the rotor control valve 320 and the lock pin control valve 330 such that the rotor control valve 320 and the lock pin control valve 330 receive hydraulic pressure from the hydraulic pump 7.

The lock pin control oil passage 410 is adapted that one end thereof is communicated with the lock pin control valve 330 and the other end thereof is branched by three so as to be communicated with the lock pin 140 through one of three such that the lock pin 140 receives hydraulic pressure from the lock pin control valve 330. Herein, the two other ends which are not the one communicated with the lock pin 140 of the branched three other ends of the lock pin control oil passage 410 will be described later.

The first rotor control oil passage 420 is adapted that one end thereof is communicated with the rotor control valve 320 and the other end thereof is communicated with the first chamber 130 such that the first chamber 130 receives hydraulic pressure from the rotor control valve 320.

The second rotor control oil passage 430 is adapted that one end thereof is communicated with the rotor control valve 320 and the other end thereof is communicated with the second chamber 132 such that the second chamber 132 receives hydraulic pressure from the rotor control valve 320.

The first regulating valve 441 is interposed on the first rotor control oil passage 420 so as to regulate hydraulic pressure being supplied into the first chamber 130 depending on the control of the controller 5. Herein, one of the two other ends, which are not the one communicated with the lock pin 140 of the other ends of the lock pin control oil passage 410, is communicated with the first regulating valve 441. In addition, the first regulating valve 441 regulates hydraulic pressure being supplied through the first rotor control oil passage 420 and hydraulic pressure being supplied from the lock pin control oil passage 410 to desired set values so as to transmit it into the first chamber 130.

The second regulating valve 442 is interposed on the second rotor control oil passage 430 so as to regulate hydraulic pressure being supplied into the second chamber 132 depending on the control of the controller 5. Herein, the other one of the two other ends, which are not the one communicated with the lock pin 140 of the other ends of the lock pin control oil passage 410, is communicated with the second regulating valve 442. In addition, the second regulating valve 442 regulates hydraulic pressure being supplied through the second rotor control oil passage 430 and hydraulic pressure being supplied from the lock pin control oil passage 410 to desired set values so as to transmit it into the second chamber 132.

In FIG. 4, a state where the rotor 120 is parked by the lock pin 140 is illustrated.

The lock pin 140 maintains the state of parking the rotor 120 when the lock pin control valve 330 is closed such that hydraulic pressure is not supplied in a state where the first regulating valve 441 and the second regulating valve 442 are closed.

Meanwhile, the lock pin 140 maintains the state of parking the rotor 120 when hydraulic pressure being supplied from the lock pin control valve 330 to the lock pin 140 is less than the set value in a state where the first regulating valve 441 and the second regulating valve 442 are opened. At this time, hydraulic pressure being supplied into the first chamber 130 and the second chamber 132 by opening the first regulating valve 441 and the second regulating valve 442 do not relatively rotate the rotor 120 but perform an assist control for providing stability.

In FIG. 5, a state where the lock pin 140 releases the parking of the rotor 120 is illustrated.

The lock pin 140 releases the parking of the rotor 120 when hydraulic pressure being supplied from the lock pin control valve 330 to the lock pin 140 is equal to or more than the set value in a state where the first regulating valve 441 and the second regulating valve 442 are opened. At this time, hydraulic pressure being supplied into the first chamber 130 and the second chamber 132 by opening the first regulating valve 441 and the second regulating valve 442 rotate the rotor 120 with relative.

Herein, the performances thereof can be changed according to a design by a person of an ordinary skill in the art such that the rotor control valve 320 and the lock pin control valve 330 regulates hydraulic pressure and the first regulating valve 441 and the second regulating valve 442 opens/closes the oil passages.

Hereinafter, the two-step type variable valve lift apparatus 200 being applied to the variable valve system 1 according to one form of the present disclosure will be described referring FIG. 6 and FIG. 7. Meanwhile, the two-step type variable valve lift apparatus 200 which will be described below is only one example, so a design of the two-step type variable valve lift apparatus 200 for varying the lift of the valve 50 by two in the variable valve system 1 may be variously changed.

FIG. 6 is a top plan view of a two steps type variable valve lift apparatus.

As shown in FIG. 6, the two steps type variable valve lift apparatus 200 includes: an outer body 210, an inner body 220, a roller 230, a connecting shaft 240, and a lost motion spring 250.

The outer body 210 is adapted to make a lever motion by selectively receiving torque of a camshaft 3, and is operated to open/close the valve 50. In addition, a cam 30 is formed or disposed at the camshaft 3 so as to transform rotational motion of the camshaft 3 to lever motion of the outer body 210. Further, a space 212 into which the outer body 210 is penetrated in a vertical direction is formed inside of the outer body 210. That is, the outer body 210 has a set length so as to make a lever motion, and has a set width and a set thickness so as to form the inside space 212 of the outer body 210.

The valve 50 is connected to one end of the outer body 210, and a rotation axis of the lever motion is disposed at the other end thereof. In addition, the inside space 212 of the outer body 210 is opened toward the one end side of the outer body 210 such that an entire shape of the outer body 210 is formed in a “U” shape.

In description hereinafter, one end and the other end each elements which are connected to or disposed at the outer body 210 mean a portion on the same side with the one end and the other end of the outer body 210.

The inner body 220 is disposed in the inside space 212 of the outer body 210. In addition, one end of the inner body 220 is rotatably connected with the one end of the outer body 210. Further, the inner body 220 is adapted to make a lever motion by receiving torque of a camshaft 3, and is operated to selectively open/close the valve 50. Furthermore, a space 224 into which the inner body 220 is penetrated in a vertical direction is formed inside of the inner body 220. That is, the inner body 220 has a set length so as to make a lever motion, and has a set width and a set thickness so as to form the inside space 224 of the inner body 220.

The roller 230 is disposed in the inside space 224 of the inner body 220. In addition, the roller 230 is rotatably connected with the inner body 220. Meanwhile, a roller rotation shaft 235 is provided for rotatably connecting the roller 230 with the inner body 220. That is, the roller 230 rotates around the roller rotation shaft 235. Furthermore, the roller 230 is rolling-contacted with the cam 30 so as to transform rotational motion of the camshaft 3 to lever motion of the outer body 210 or the inner body 220. Herein, the cam 30 being contacted to the roller 230 is the high cam 32.

The connecting shaft 240 connects the first end of the outer body 210 with the first end of the inner body 220 such that they can rotate. That is, the inner body 220 can rotate about the connecting shaft 240 relative to the outer body 210. The first end of the outer body 210 connected with the inner body 220 by the connecting shaft 240 is referred to as an outer connecting portion 214, and the first end of the inner body 220 connected with the outer body 210 by the connecting shaft 240 is referred to as an inner connecting portion 222.

A valve contact portion 216 is formed or disposed close to the outer connecting portion 214 at the first end of the outer body 210. Two outer connecting portions 214 may be formed at the first end of the outer body 210 that are open to a side. Accordingly, two valve contact portions 216 may be formed or disposed close to the two outer connecting portions 214, respectively. The case of forming the valve contact portions 216 by two is a case that the two valves 50 are opened or closed depending on the lever motion of the outer body 210 as the two valve contact portions 216 are respectively contacted to the valve 50.

The inner body 220 may be selectively fixed to the outer body 210 and may pivot with it, or may be selectively unfixed from the outer body 110 and may independently pivot.

The lost motion spring 250 returns the inner body 220 that has rotated relative to the outer body 210 by independently pivoting, when the inner body 220 is unfixed from the outer body 210

FIG. 7 is a cross sectional side view of a two-step type variable valve lift apparatus according to the present disclosure.

As shown in FIG. 7, the inner body 220 further includes a latching pin hole 229, and a latching pin 260, a stopper 267, and a latching spring 265 are disposed in the outer body 210.

The latching pin hole 229 is formed such that the latching pin 260 is inserted therein. The latching pin 260 is operated by hydraulic pressure, and may be disposed at the second end of the outer body 210 to be easily supplied with hydraulic pressure. Meanwhile a component for supplying hydraulic pressure such as an HLA (Hydraulic Lash Adjuster) 90 may be disposed at the second end of the outer body 210. Herein, a construction and a function of the HLA 90 which is generally positioned at a cylinder block so as to transmit hydraulic pressure are well known to a person of an ordinary skill in the art, so detailed description thereof will be omitted.

The stopper 267 is provided to inhibit or prevent that the latching pin 260 is escaped toward the other end direction of the outer body 210.

The latching pin 260 is inserted into the latching pin hole 229 by elastic force of the latching spring 265 such that the inner body 220 may be fixed to the outer body 210. That is, the latching spring 265 is a spring which is disposed between the stopper 267 and the latching pin 260 such that one end of the latching spring 265 pushes the latching pin 260 toward the inner body 220. In addition, a hydraulic pressure chamber 269 which is surrounded by the outer body 210 and the latching pin 260 is formed at the one end side of the latching pin 260. Further, the latching pin 260 is pushed toward the other end direction of the outer body 210 by hydraulic pressure supplied to the hydraulic pressure chamber 269 such that the inner body 220 is released from the outer body 210. In other words, the latching pin 260 is returned by the latching spring 265 so as to be inserted into the latching pin hole 229 such that the inner body 220 is fixed to the outer body 210 in case that hydraulic pressure supplied to the hydraulic pressure chamber 269 is released.

The two-step type variable valve lift apparatus 200 according to one form of the present disclosure is provided to selectively realize two step lifts including the high lift and the low lift of the valve 50.

Meanwhile, the design of the two-step type variable valve lift apparatus 200 may be changed such that the inner body 220 is fixed to the outer body 210 during supplying hydraulic pressure into the hydraulic pressure chamber 269 as the latching spring 265 and the hydraulic pressure chamber 269 are disposed to the opposite position with respect to the latching pin 260 and the latching spring 265 functions as a return spring to return the latching pin 260 during releasing hydraulic pressure.

If the inner body 220 is fixed to the outer body 210, the inner body 220 and the outer body 210 make a lever motion together around the rotation axis of the lever motion of the outer body 210 depending on rotation of the high cam 32 rolling-contacted with the roller 230. Thus, the high lift of the valve 50 is performed.

If the inner body 220 is released from the outer body 210, only the inner body 220 makes a lever motion around the connecting shaft 240 depending on rotation of the high cam 32 rolling-contacted with the roller 230. At this time, the low lift of the valve 50 is performed as the outer body 210 makes a lever motion by the low cam 34 being contacted to the outer body 210.

FIG. 8 is a hydraulic circuit diagram of a two-step type variable valve lift apparatus according to one form of the present disclosure.

As shown in FIG. 8, the two-step type variable valve lift apparatus 200 further includes a hydraulic pump 7, an oil control valve 550 and a hydraulic pressure line 500.

The hydraulic pump 7 pumps oil so as to generate hydraulic pressure desired for operating the latching pin 260 depending on the control of the controller 5. In addition, the hydraulic pump 7 may be the same member with the hydraulic pump 7 which pumps oil so as to supply hydraulic pressure desired for operating the intermediate phase CVVT apparatus 100, but it is not limited thereto.

The oil control valve 550 functions to selectively supply hydraulic pressure transmitted from the hydraulic pump 7 depending on the control of the controller 5 to the HLA 90. Meanwhile, the oil control valve 550 may be a general OCV (oil control valve), and the basic construction and function of the oil control valve 550 are well known to a person of an ordinary skill in the art, so detailed description thereof will be omitted.

The hydraulic pressure line 500 transmits hydraulic pressure as an oil passage and includes a first hydraulic pressure line 510 and a second hydraulic pressure line 520.

The first hydraulic pressure line 510 communicates the hydraulic pump 7 with the oil control valve 550, and the second hydraulic pressure line 520 communicates the oil control valve 550 with the HLA 90. As this, the composition of the hydraulic circuit to supply oil for operating the two steps type variable valve lift apparatus 200 is enough by only the configuration of the one oil control valve 550 and the hydraulic pressure line 500 positioned via this.

According to the present disclosure, applicability to be aimed various engines may be expanded, fuel consumption efficiency may be improved, and responsiveness can be advanced as the two-step type variable valve lift apparatus 200 having a simple composition of hydraulic circuit supplying hydraulic pressure is applied, and simultaneously, the continuously variable valve timing apparatus 100 is applied. In addition, production cost may be decreased by the simple composition and fuel consumption can be improved by the reduction of weight.

While this present disclosure has been described in connection with what is presently considered to be practical exemplary forms, it is to be understood that the present disclosure is not limited to the disclosed forms, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the present disclosure. 

What is claimed is:
 1. A variable valve system which is applied to an engine being configured that a rotational motion of a cam being formed or disposed at a camshaft so as to rotate together with the camshaft is converted to a reciprocating motion of a valve for opening or closing a combustion chamber, the variable valve system comprising: a two-step type variable valve lift apparatus configured to perform a lever motion and configured that one end of the two-step type variable valve lift apparatus is in rolling-contact with the cam and an other end of the two-step type variable valve lift apparatus is in contact with the valve so as to perform one of two lifts of the valve; and a continuously variable valve timing apparatus configured to change a phase of the camshaft connected with a rotor as the rotor rotates by rotating a vane formed at the rotor so as to selectively change opening or closing timing of the valve.
 2. The variable valve system of claim 1, wherein the variable valve system is applied to an intake side of the engine and the valve is an intake valve which is operated so as to supply intake air into the combustion chamber.
 3. The variable valve system of claim 1, wherein the variable valve system is applied to an exhaust side of the engine and the valve is an exhaust valve which is operated so as to discharge exhaust gas from the combustion chamber.
 4. The variable valve system of claim 1, wherein the continuously variable valve timing (CWT) apparatus is an electric continuously variable valve timing apparatus which is operated electrically.
 5. The variable valve system of claim 1, wherein the continuously variable valve timing apparatus is an intermediate phase continuously variable valve timing (CVVT) apparatus which is operated by hydraulic pressure so as to have a parking position which is an intermediate phase between a maximal advance position and a maximal retard position.
 6. The variable valve system of claim 1, wherein the two lifts of the valve being realized by the two-step type variable valve lift apparatus are a high lift and a low lift, and the two-step type variable valve lift apparatus is configured to perform the high lift by supplying hydraulic pressure and to perform the low lift by releasing the hydraulic pressure.
 7. The variable valve system of claim 1, wherein the two lifts of the valve being realized by the two-step type variable valve lift apparatus are a high lift and a low lift, and the two-step type variable valve lift apparatus is configured to perform the low lift by supplying hydraulic pressure and to perform the high lift by releasing the hydraulic pressure.
 8. The variable valve system of claim 1, wherein the two-step type variable valve lift apparatus comprises: an outer body configured to selectively make a lever motion depending on rotation of the cam and configured such that the valve is connected with one end of the outer body, a rotation axis of the lever motion is disposed at an other end of the outer body, and an inside space is formed in the outer body; an inner body disposed in the inside space of the outer body and adapted that one end of the inner body is rotatably connected with the one end of the outer body; a connecting shaft disposed to penetrate the one end of the outer body and the one end of the inner body so as to connect the outer body with the inner body; and a lost motion spring configured to return the inner body being relatively rotated with the outer body around the connecting shaft.
 9. The variable valve system of claim 8, wherein the inner body is configured to perform a lever motion together with the outer body depending on the rotation of the cam around the rotation axis of the lever motion of the outer body during being selectively fixed to the outer body, and the inner body is configured to perform a lever motion alone depending on the rotation of the cam around the connecting shaft during releasing from the outer body.
 10. The variable valve system of claim 9, wherein the two-step type variable valve lift apparatus is configured to perform a high lift of the valve as the outer body makes the lever motion together with the inner body, and configured to perform a low lift of the valve as only the inner body makes a lever motion around the connecting shaft.
 11. The variable valve system of claim 8, wherein the inner body forms an inside space and the two-step type variable valve lift apparatus further comprises a roller disposed in the inside space of the inner body and rotatably connected with the inner body so as to rolling-contact with the cam so that the inner body makes a lever motion depending on the rotation of the cam. 